1. Field of the Invention
The invention relates to signal processing systems, and in particular to a system for providing real-time correction of nonuniformities in signals from a plurality of signal sources, such as from a detector array.
2. Description of the Prior Art
The response of a given detector cell in a mosaic array of sensors usually increases monotonically with excitation and exhibits no hysteresis. Deviation from linearity is hoped to be (but often isn't) small; therefore the detector often is modeled as a linear device (without dynamics), described by its bias and gain. Since the bias and gain are different for each cell, calibration and correction procedures are used to adjust the bias and scale factor of each cell to attempt a reasonably uniform response among the detectors of the array. (J. P. Rode, "Nonuniformity Correction in a Multielement Detector Array," U.S. Pat. No. 4,298,887, Nov. 3, 1981). Those focal planes must be rejected whose cell responses are not readily approximated by single straight-line segments over the operating range. Real cells exhibit responses that are not only nonlinear, but slowly time (actually temperature or other environmental-parameter) varying. However, the absolute linearity of each response is not as important as the uniformity of the corrected response from cell to cell.